Duration should be reasonably short, distance for communicating back is fairly low. No issue with distance from the Sun for solar panels. Flyby would give useful info, and might not have to be at huge speed (depending on SC lifetime).

Cheers, Martin

A big problem is propulsionIt is safe to assume that the delta-V in the NHATS models is equally distributed among the three.That means the flyby needs ~2.5 km/sec.That's a lot of propulsionCubesats rarely have any, and none have had 1% of this. And you know the tyranny of the rocket equation.And no cubesats have had high Isp SEP.

A dot. Resolution of Hubble at that distance should be 5 km for violet/soft UV wavelengths.

What sort of image could we expect from JWST of this object?

JWST is bigger, but it's also restricted to longer wavelengths so its maximum resolution should still be >4 km. You'd need a diffraction limited telescope with a 100m main mirror (or an interferometer with a baseline of that magnitude) to resolve this asteroid. For pretty pictures, sending something close to it is the only real option....

Duration should be reasonably short, distance for communicating back is fairly low. No issue with distance from the Sun for solar panels. Flyby would give useful info, and might not have to be at huge speed (depending on SC lifetime).

Cheers, Martin

A big problem is propulsionIt is safe to assume that the delta-V in the NHATS models is equally distributed among the three.That means the flyby needs ~2.5 km/sec.That's a lot of propulsionCubesats rarely have any, and none have had 1% of this. And you know the tyranny of the rocket equation.And no cubesats have had high Isp SEP.

Thanks. You're right - I was thinking about this more like a standard NASA probe, where the launcher u/s pushes the stage beyond escape, rather than it having to do the injection itself.

But, of course, the point with such a small sat is either to be a secondary, or to launch on a dedicated smallsat launcher, and who's offering a BLEO smallsat launcher?

OTOH, such a sat as secondary on a Super Synchronous Transfer mission could be taken pretty close to escape. Whether that would put it anywhere close to the right vector for transfer is a separate question.

Secondary thought - if the u/s has any residuals after SSTO injection for a disposal burn, that could well go to escape, anyway?

In terms of suitable launchers, Atlas V has dial-a-rocket with options for number of solids, and F9 usually seems to be launching close to its limits on Super Synchronous injections. This would only be possible for very small primary payloads, or FH?

Or you can ensure that the payload has enough delta-v to get to the asteroid without a perfect boost like PR's planned spacecraft. This asteroid should be accessible to an Arkyd 200.

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For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v. Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

As to how you'd get something into such an orbit, it would likely be from debris from the Earth or Moon, either from formation or as part of a collision, where such escaped but not by much, and by accident entered a weak stability region between the Earth Moon Sun ensemble, staying there ever since.

The most interesting part of this is "how long" has it been there? During the formation of the solar system, much has been swept away, so if it has been there a long time, why wasn't it dislodged?

If it hasn't been there long, the capture event would be unique, and likely the result (again) of an encounter.

As to visiting it, a lunar encounter with a phased entry into the same gravitational equipotential would be the obvious choice, like entering a Lissajous orbit. If your US were long lived enough for a post lunar burn you could save much time (down to a few months), but if we're being economical, a hundred kilogram SEP craft that shared a GTO-1800 ride as a secondary might make it in a few years or less, depending on launch and if you could coax a third burn post primary payload, and the moon's position. Such a mission would take longer to design/fund/build/launch then to fly

My family is having a good laugh imagining that this object is actually the lid from Operation Plumbob Pascal-B test.Especially after we read that "calculations indicate 2016 HO3 has been a stable quasi-satellite of Earth for almost a century".

A dot. Resolution of Hubble at that distance should be 5 km for violet/soft UV wavelengths.

What sort of image could we expect from JWST of this object?

JWST is bigger, but it's also restricted to longer wavelengths so its maximum resolution should still be >4 km. You'd need a diffraction limited telescope with a 100m main mirror (or an interferometer with a baseline of that magnitude) to resolve this asteroid. For pretty pictures, sending something close to it is the only real option....

Its apparent magnitude should be about 19 when the object is closest to earth, if I did the math right. So it looks like none of the existing interferometers are up to the task.

I checked your math, and it looks about right.

But we may build interferometers that work up to 19 magnitude. We have some extremely large telescopes coming online, and we may start building interferometers with large baselines using them. Also, fringe-tracking is improving the limiting magnitude of these interferometers.

...but it'll be a while.

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

That's a great presentation. I had forgotten about Busek. They are making great progress and proposing a mission quite like one to 2016 HO3, although possibly easier to reach. It requires less delta-V, albeit possibly one launch window instead of 2016 HO3's yearly window.

A great advantage of cubesats are their standardization and low cost, for both hardware and launch. Asteroid rendezvous could use a standardized spacecraft. A second mission would be even more economical than the first.

The new small LVs in development may just be able to deliver a cubesat or two to earth escape velocity. If Moon express MX1e can land on moon using Electron LV, then cut down version of MX1e could give a 6U cubesat around 6km/s.

The fact that the solar wind doesn't perturb it much (hundreds of years stability) suggests a high density.

That would be (kinda, see below) true if that stability had been observed. It hasn't, of course, because we only found it two months ago. Instead, the stability is inferred from modelling its movement in an n-body integrator over some time. I doubt that this integration even considered non-gravitational effects (because this would require additional knowledge about the object we don't have).

Also, solar wind is negligible on that scale. What you mean are Yarkovsky/YORP effects. Although I doubt they will have much of an effect over the scale of centuries.

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Since it is close for such a body

Its distance to us doesn't depend on its size/density. Its distance to Earth comes from its movement around the sun. In fact, its the other way around: its size depends on the observed brightness, the observed distance, and the assumed albedo. If we were to get the thermal emission, we could calculate the likely size (although thats not perfect either).

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As to how you'd get something into such an orbit, it would likely be from debris from the Earth or Moon, either from formation or as part of a collision, where such escaped but not by much, and by accident entered a weak stability region between the Earth Moon Sun ensemble, staying there ever since.

An ejection from the Moon is a possibility (which has been suggested before for a peculiar NEO, 2000 SG344). Or, it might just be a normal asteroid that was diverted into that orbit by a close encounter with Earth and/or the Moon. Over long time-scales and many trials, even unlikely things are bound to happen eventually.

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The most interesting part of this is "how long" has it been there? During the formation of the solar system, much has been swept away, so if it has been there a long time, why wasn't it dislodged?

Since the stability of its current orbit is on the order of centuries, its a safe bet that it has been in that orbit "on the order of centuries". Before that (and after that), it likely came from (and will go back to) the NEO population.

Magnitude per JPL Horizons won't get brighter than recently, in the near future won't get brighter than ~22nd mag. Might change with better obs but going on prior results it's hard to find.

See attached for plot of predicted mag and distance. Later it gets closer again but phase angle is worse.

Nice!

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

the orbit is locked into a very odd figure-8 pattern that does not seem realistic to be either an artificial satellite launched from Earth or a natural satellite of Earth or asteroid. Taking into consideration [all of the] gravitation and solar forces on the object, this orbital pattern is about as strange as has ever been seen.

Thought you all might like a link to the original source of this. It's a very strange orbit indeed. Always roughly in the direction of Leo / Virgo, in a figure of eight orbit as seen from Earth - so sometimes closer to the sun, sometimes further away but always in roughly the same absolute direction from Earth. It's very accessible from Earth, in terms of delta v anyway if not bothered about the duration - seems to be slightly easier to reach than the EML2 for its minimum energy orbit and slightlier easier to reach than the Moon for the minimal duration orbit. See delta v table

This would allow a company like PR or DSI to explore a celestial object, and if they find any valuable minerals or ice, their discoveries would be protected like a patent, which could be subsequently assigned (sold) to other companies. Your feedback on the structure of the mining claims registry would be greatly appreciated, in that thread. Please do not waste our time debating about property claims.

the orbit is locked into a very odd figure-8 pattern that does not seem realistic to be either an artificial satellite launched from Earth or a natural satellite of Earth or asteroid. Taking into consideration [all of the] gravitation and solar forces on the object, this orbital pattern is about as strange as has ever been seen.

Thought you all might like a link to the original source of this. It's a very strange orbit indeed. Always roughly in the direction of Leo / Virgo, in a figure of eight orbit as seen from Earth - so sometimes closer to the sun, sometimes further away but always in roughly the same absolute direction from Earth. It's very accessible from Earth, in terms of delta v anyway if not bothered about the duration - seems to be slightly easier to reach than the EML2 for its minimum energy orbit and slightlier easier to reach than the Moon for the minimal duration orbit. See delta v table

That was hard for me to get my head around. I was thinking how can it stay in the same region of the sky? It makes a complete circuit about the earth every year. Then it occurred to me as it moves 360 wrt earth, the earth moves 360 wrt sun.

As to visiting it, a lunar encounter with a phased entry into the same gravitational equipotential would be the obvious choice, like entering a Lissajous orbit. If your US were long lived enough for a post lunar burn you could save much time (down to a few months), but if we're being economical, a hundred kilogram SEP craft that shared a GTO-1800 ride as a secondary might make it in a few years or less, depending on launch and if you could coax a third burn post primary payload, and the moon's position. Such a mission would take longer to design/fund/build/launch then to fly

The OP was asking about THIS object, and since we haven't had a spacecraft near it, there's nothing for it to perturb gravitationally to get a mass. What you'd do is figure a few 1000 kg/m^3 density, give a factor of 2 uncertainty (mostly on the low side in case it's like Mathilde). Given the uncertainty in the size, there's probably about a factor of 10 uncertainty in mass right now. I suspect the size can be measured pretty accurately by radar from the intensity of a reflected signal.

Given that Congress seems to want to kill ARRM, it would probably be more useful to think of a low-cost way to get a probe to the asteroid. The Japanese Procyon would likely be a good departure point for a design, but of course its SEP failure would have to be diagnosed and remedied.

If the orbit is known, the mass is known.

- Ed Kyle

[Jim]Wrong[/Jim]

That statement is incorrect. Knowing the current orbit says nothing about the mass.

edit: If orbits depended on mass, people could not occupy the ISS, as they have 1E-4 the mass of the station but co-orbit with it nicely, as do even small objects.

Tracking the orbit over years or decades can give an indication of mass due to forces other than gravity, like the Yarkovsky effect or YORP, but there doesn't appear to be enough data on 2016 H03, as the first images on PANSTARS is from 2012, four years ago.

Again, the Arkansas Sky Observatories website makes a specific statement about 2016 HO3 having a mass lower than one would expect for the brightness. It is not clear how they can make this statement. I have yet to find any paper or release with an independent measure of mass or density.

edit 2: Can you tell us how to determine the mass, Ed?

« Last Edit: 06/21/2016 08:12 PM by Comga »

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What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

The fact that the solar wind doesn't perturb it much (hundreds of years stability) suggests a high density.

I had assumed that the hundreds of years was based on projecting back from current orbit.

If it is low enough density to be perturbed, then that just seems to invalidate the assumption, IE it could be a man-made object that seems to be long term stable due to a fluke of current position.

There are many ways to handle retrospective analysis. One that comes to mind at UCLA used known observations to allow them to discover integration errors in sub arc second consistency, which for million year integrations could be checked with other means in the gross sense. Some have done likewise.

Of course, we could assume gross mathematical negligence like some, but for it to be so stable as suggested beggars the imagination too ... when your codes are wrong, they never converge.

Another way to do this is to model the cyclical variations, such that you know the impulse of known transient effects, and correlate that with the astable orbit, to determine "how long" it could survive. In that case, you are making a judgement based on the means by which the orbit is stable, not by retrospectives.

Keep in mind that it is not a "gravitation-ally bound" object. Not suspended in a Lagrange point. Not working strictly as a Keplerian object.

Also note the sizable variations in its orbit - a fair fraction of Earth-Moon distance.

Injecting an object to an orbit like this will take a lot of skill. In terms of random odds for insertion, likely in the billions if not more.

Why its likely "dense" and not man made "fluffy" is that those variations you see have exponentials tied to them, won't take much to escape into helocentric ejection - its already at/above escape velocity.

So what is retaining it is likely higher order terms of a N > 4 body problem. Where an equipotential "well" exists that is deep enough for such a mass.

With the S-IVB stage we know of (J002E3), it ejects to heliocentric and gets recaptured. Some think that this is affected by solar effects.

Again, because it is close enough that inverse square law losses for the bounce to be "brute forced", one can discern this by comparison. By all means one must decide this first. There are only so many SIVB, and the only way one could enter this orbit I can find for such would involve three significant burns post Moon, the first 4+ days after the vehicle expended ...

25 - 113 meters:Estimated diameter in meters showing the minimum and maximum likely size based on assumed maximum and minimum albedos of 0.60 and 0.03, respectively. If the size is "known", a single value is shown instead. If a single value is shown, it should still be considered an estimate.

Duration should be reasonably short, distance for communicating back is fairly low. No issue with distance from the Sun for solar panels. Flyby would give useful info, and might not have to be at huge speed (depending on SC lifetime).

Cheers, Martin

A big problem is propulsionIt is safe to assume that the delta-V in the NHATS models is equally distributed among the three.That means the flyby needs ~2.5 km/sec.That's a lot of propulsionCubesats rarely have any, and none have had 1% of this. And you know the tyranny of the rocket equation.And no cubesats have had high Isp SEP.

We're working on a cubesat heliogyro solar sail under a NASA SBIR contract we just started. Still just in Phase I, so a long way to go, but it might be a way to do a mission like this...

A cubesat definitely /could/ have high-Isp propulsion. Just because none have so far doesn't mean they couldn't.

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0